I have a 9700pro and am getting an Apple 20 inch cinema display in the next couple of weeks. I was wondering if I should upgrade to a X800xl which i can get for $360 canadian. I would like to run my games at native resolution (1680 x 1050). Is it worth it if i have

AthlonXP 2600
1gb corsiar 3200xlpro
A7N8X deluxe mobo (rev1.04)

or would i need to upgrade more than just the video card. I don't want to do it if i need to upgrade more than the video card. I'll just run the games in a window.